Nerve and brain injuries, including traumatic and degenerative injuries to peripheral nerves and/or the spinal cord (SCI), still remain with no curative therapy. With respect to SCI for example, even a mild contusion to the spinal cord can result in massive neuronal and glial cell loss, demyelination, cavitation, and glial scarring. Pathological changes such as these have detrimental functional effects causing loss of sensory perception, distal motor paralysis, and severe functional impairment, with the final outcome depending upon axonal sparing, remyelination, and possibly neural regeneration. Similar effects are also observed with many neurodegenerative disorders including, inter alia, Alzheimer's Disease, Parkinson's Disease, Multiple Sclerosis, Amyotriphic Lateral Sclerosis, multiple-system degenerations, cerebellar degeneration, and the like. Accordingly, one or more strategies are desirable to repair or regenerate damaged tissue with the ultimate outcome of restoring such tissue and lost functional effects.
One proposed strategy is the use of pluripotent cells or stems cells for the purposes of treating the affected area. Marrow stromal cells, in particular, are attractive candidates for such purposes because they have many of the characteristics of stem cells and have been shown to differentiate into osteoblasts, chondrocytes, adipocytes, and even myoblasts. Thus, there is potential for their use in regenerating damaged nervous or brain tissue in a patient.
One of the primary difficulties is that marrow cell types are relatively rare and difficult to identify. To this end, much of the current research has been centered around isolating particular cell types of interest and exploring methodologies for achieving neural cell differentiation. U.S. Patent Application Publication No. 2007/0031387, for example, discloses the isolation of mononuclear cells from granulocytes within a population of bone marrow cells. U.S. Pat. No. 7,098,027 alternatively isolates mononuclear cell isolation using density-gradient centrifugation, i.e. by isolating cells having a specific gravity within the range of 1.07 and 1.08 g/ml. In either of the two cases, the isolated mononuclear cells are contemplated for administration for treatment of spinal injury or other neurological disorders.
Beyond cell isolation, there have been numerous attempts to differentiate BM cells either before administration in an in vitro environment or after administration in vivo. U.S. Pat. No. 5,197,985, for example, illustrates methods for regenerating mesenchymal and neuroectodermal tissues using adult bone marrow (BM) cells. Cell differentiation is accomplished using a porous ceramic composition of tri-calcium phosphate or hydroxyapatite or combinations of the two, as a vehicle or carrier for marrow-derived mesenchymal cells, which, when implanted into skeletal defects, promotes the differentiation of the cells into skeletal tissue.
U.S. Pat. No. 6,528,245 discloses a method of specifically selecting for bone marrow stromal cells in a bone marrow cell population by incubating the cells in a plastic culture medium and removing the stromal cells that adhere to the plastic. These cells are then differentiated in vitro in the presence of retinoic acid, growth factors, and fetal neuronal cells and are administered for treating neurodegenerative disorders. U.S. Patent Application Publication No. 2006/0275272 similarly teaches treatment methods by isolating and culturing bone marrow stromal cells to be used for such purposes. Finally, U.S. Pat. No. 7,279,331, teaches similar methods of isolating bone marrow stromal cells, which are then pre-differentiated in vitro into a neuronal cell using antioxidants and/or various growth factors.
U.S. Patent Application Publication No. 2006/0029580 further teaches a method of generating neural progenitor cells by incubating bone marrow cells in a culture supplemented with fibroblast growth factor-2 (FGF-2) and epidermal growth factor (EGF). The progenitor cells may then be administered to a patient exhibiting a neuropathologic condition.
Beyond BM cells, cells derived from placental or other post-natal tissue have also been explored for neural regenerative purposes. U.S. Patent Application Publication No. 2006/0147426 relates to cell culture conditions for isolating post-natal, multilineage inducible cells. Such culture conditions include extracellular matrix substrate, oxygen tension, growth factors and vitamins, cell density, or co-culture of cells. U.S. Patent Application Publication No. 2005/0032209 teaches methods and compositions for regenerating or repairing neural tissue using postpartum-derived cells. These cells are derived from placental or umbilical cord tissue and are grown on L-valine media in a 5% oxygen environment.
The foregoing presents definitive evidence that bone marrow and similar pluripotent cell types can differentiate into mesenchymal cells, and further illustrates the feasibility and promise of applying these cell types for treatment of traumatic or degenerative injury to nerve or brain tissue, such as remyelination or regeneration of damaged axonal tissue. Even in view of the proposed methodologies above, however, there remains a need for alternative cell populations and novel strategies for more predicable cell differentiation. In addition, there is a need to circumvent the numerous ethical and technical constraints that now limit the widespread use of neural transplant.
The instant invention through its embodiments and examples addresses these needs.